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Major Contributor

Well it's a cheap an cheerful DAC with a BoM of less than $30, so believe me I was not losing sleep over it. Since Amir commenting on design and parts I figured I'd point out that the layout could easily have been improved.

Major Contributor

As good a guess as any, Amir. I've not thought about it. I'd have to look up the chips and guesstimate what makes most sense at the system level, but it's a cinch that an inexpensive DAC with great performance is going to minimize components, and using the cleanest clock to drive the DAC then buffering it to everything else seems reasonable. An independent DAC oscillator is going to cost more, femtosecond jitter or not... Even 100 ps of jitter does not degrade SNR much at audio frequencies and remember (for others, I know you know this, Amir) that the impact of jitter depends upon the signal frequency, not the sampling rate (clock frequency).

Don Herman
"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley

Addicted to Fun and Learning

As always its about implementation and the effects of any actual real world design rather than audiophile dogma. The performance of clock transmission lines can be analysed and optomised. This is nothing unusual rf work.

Whack a femto clock in there, that will solve your problems any audiophile knows this.

New Member

I got the D30 - Not sure if this thread deals with repairs ( reading the text seems to say - not to try to repair - BUt - i am sucker for pain)

I had the d30 for about 7 months and lost analog out. Windows still registers the USB dvice- BUT I don't think that is where the problem is.

I did the static measurments at the test points and I can see that the Vd on the cs4398 is sitting at 2.4 V instead of 3.3. Which seems to imply that the digital part of CS4398 is simply not working - hence no sound out.

so my question - has anybody done a trace of the schematics? or DOES anybody have a schematics of the D30. My suspcion is some capacitor ( either the 10uF or the 0.1 uF going bad and shorting to ground. OR any of the elemnts in the Lm 117 circuitary.

Looking at the pictures on the previous page, one of the LM 117 ( 3.3V) is used to feed the Vd. This one gets very hot to the touch. also on the same picture, there are a group of resistors and caps circled as being in the circuit of the regulator. Is this correct?

I do have some fo the other negative voltages out of spec( -15 V is actualy more like -13.5) but the OpAmp seems to be getting good volates of +, _ 11v on the pins. so this may or may not be a problem. However I can not tell without a diagram.

I know I can try and get warranty But my attempts through Aliexpress have so far resulted with nothing and I am happy to crank up the soldering iron ( can do SMD work if needed).

another symptom - tried to use it through Optical and it does not even sync. looking at the picture above - if CS4398 is not active because of low Vd, you would not expect the optical to do anything useful.

Any suggestions or help appreciated. If this needs to go to a different thread - please let me know - or help me move it.

New Member

The Lm 1117 3.3 generating the 3.3v VD is overheating. works for a few seconds with a good voltage, then overheats - and I mean melting plastic voerheat - probably 70 degrees celsius plus.

The circuit is textbook- nothing odd, adj to ground, 2 caps in paralel with 180 ohm resistance on input same on output ( no resistance ). resistance to ground from pin 7 on CS4398 is around 460ohm ( DC conditions). the caps don;t show any shortson DC - so the ptions are caps out of spec, or lm1117 gone to oscilation generating high heat and shutting down. Could be bad lm1117. I can hear high pitch noise after about 5 seconds power even without any amplifier plugged in- more like mechanical 8 khz noise.

So next step will be to do cap and lm 1117 swap. worst option CS4398 is dead and Iit is just to much soldering in that case.

New Member

Alas, the Seller on ali express stopped responding, so I will go directly to topping - frankly I'd be happy to get the board and do a swap myself
Thanks for listening - I love the D30 though. Temporarily I am Using Sabaj DA3 it is actually really good both phones connected directly and also going through headphone amp.

Active Member

Hi, first I want to thanks Amir for all his work and knowledge sharing with the audio community.

Regarding the D30 I've noticed that in different board revisions they use different oscillators. Has someone been able to identify the black apparently programable Silicon based ones labelled as 80GFP, I'm just curious about what they are using.

Active Member

The oscillators that I refer to are the ones used in the board revision that you measured (10.1), but they are difficult to identify, they are a bit unusual since normally quartz based ones are used in this kind of application; anyway they seem to work well given the good jitter measurement results.

Active Member

I already searched for both combinations before asking, I'm curious because silicon based oscillators aren't normally used for audio, old school quartz ones offer better specs except for resistance to vibration and temperature, and cost should be similar, so it's a pretty weird design choice.

Member

The only miss on this front is a front panel switch that selects between digital sources. So signals have to be routed way up there and back. This switch would have been best put in the back. I guess convenience trumped that engineering fidelity.

Founder/Admin

I already searched for both combinations before asking, I'm curious because silicon based oscillators aren't normally used for audio, old school quartz ones offer better specs except for resistance to vibration and temperature, and cost should be similar, so it's a pretty weird design choice.